P1133

Oxygen Sensor 1 (O2S 1) Circuit:

System Description
The Powertrain Control Module (PCM) continuously monitors the Oxygen Sensor 1 (O2S 1) activity for 100 seconds. During the monitor period, the PCM counts the number of times that the O2S 1 switches from rich to lean and from lean to rich. With this information, a total for all switches can be determined. Whenever the number of switches is below a calibrated value, a DTC P1133 will be set.

Conditions for Setting the DTC
- When one or more of the following DTCs are not present P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0300, P0301, P0302, P0303, P0304, P0506, P0507, P1441.
- The number of lean to rich counts is less than 15 or the rich to lean counts is less than 10.
- The engine speed is between 1600 RPM and 2600 RPM.
- The TP angle is between 8.0% and 20%.
- The evaporative emissions control system is commanded open for greater than 60% PWM.
- The purge learn memory is greater than approximately 191.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the fault active.
- The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC
- The MIL will turn OFF" after three consecutive ignition cycles in which the diagnostic runs without a fault.
- A history DTC will clear after 40 consecutive warm up cycles without a fault.
- DTCs can be cleared by using a scan tool.

Diagnostic Aids
DTC P1133 is most likely caused by one of the following conditions:
- Fuel pressure - The system will go rich if fuel pressure is to high. The PCM can compensate for some increase, however, if it gets too high, a DTC P0132 will set. Refer to Fuel System Diagnosis, Table A-6.
- Leaking injector - A leaking or faulty fuel injector can cause the system to go rich.
- MAP sensor - An output that causes the PCM to sense a higher than normal manifold pressure (low vacuum) can cause the system to go rich. Disconnecting the MAP sensor will allow the PCM to set a fixed value for the MAP sensor. Substitute a different MAP sensor if the rich condition is gone while the sensor is disconnected.
- Pressure regulator - Check for a leaking fuel pressure regulator diaphragm by checking for the presence of liquid fuel in the vacuum line to the regulator.
- TP sensor - An intermittent TP sensor output will cause the system to go rich due to a false indication of the engine accelerating.
- O2S contamination - Inspect the O2S for silicone contamination from fuel or use of RTV sealant. The sensor may have a white powdery coating. This can result in a high but false voltage signal (rich exhaust indication).

DTC P1133 - Oxygen Sensor (O2S) Insufficient Switching Sensor 1 (1 Of 2):

DTC P1133 - Oxygen Sensor (O2S) Insufficient Switching Sensor 1 (2 Of 2):

Test Description
Numbers below refer to the step numbers on the Diagnostic Table.
1. The OBD System Check prompts the Technician to complete some basic checks and store the Freeze Frame Data and the Failure records on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. This information on the scan tool can be referred to later.
16. Before replacing the PCM, check terminals for improper mating, broken locks, or physical damage to the wiring harness. Replacement PCM must be reprogrammed. Refer to the latest Techline information for programming procedures.